1. Field of the Invention
This invention concerns a coating composition with excellent abrasion resistance suitable to the surface coating of a substrate such as of metals, fiber-reinforced plastics (hereinafter simply referred to as FRP) and other plastics.
2. Description of the Prior Art
As metals, FRP and other plastic materials have been used more and more in electric and electronic applications in recent years, an improvement is demanded for the surface durability of these substrate materials such as abrasion resistance and scratch resistance.
Various methods of surface treatment through abrasion-resistant coating have been proposed for improving the durability of metal materials and wooden floor materials, for instance, as described below:
(1) a composition comprising from 0.5 to 30% by weight of mineral substances mainly composed of aluminum oxide and from 1 to 50% by weight of fiberous substances incorporated through dispersion to an acid curing type amino alkyd resin or moisture-curing type polyurethane resin solid (Japanese Patent Publication No. 35487/1976),
(2) a composition comprising from 5 to 7.5 parts by weight of .alpha.-alumina and from 2.5 to 5.0 parts by weight of silicon carbide blended with 100 parts by weight of a urethane resin (Japanese Patent Publication No. 33475/1980),
(3) a coating composition comprising highly hard ceramics incorporated and dispersed into an abrasion-resistant thermoplastic resin (Japanese Patent Laid-Open No. 4930/1979), etc.
However, any of the compositions (1) and (2) is used for improving the durability of floor materials and it is difficult to provide a high surface durability demanded for metal, FRP, plastics in electric and electronic applications. In addition, the compositions have only an insufficient adhesion property for these materials. Further, the abrasin-resistant thermoplastic resin in the above composition (3), for example, nylon, polyacetal or teflon has an insufficient adhesion property for metal, FRP, plastics and can not provide a surface coating treatment of high abrasin resistance and scratch resistance.